<template>
  <div>
    <p>请选择你要购买的书籍</p>
    <ul>
      <li v-for="item in arr" :key="item.id">
        {{ item.name }}
        <button @click="btn(item.id)">买书</button>
      </li>
    </ul>
    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="item in arr" :key="item.id">
        <th>{{ item.id }}</th>
        <th>{{ item.name }}</th>
        <th>{{ item.price }}</th>
        <th>{{ item.count }}</th>
        <th>{{ item.total }}</th>
      </tr>
    </table>
    <p>总价格为: {{ sum }}</p>
  </div>
</template>
<script>
export default {
  data() {
    return {
      arr: [
        {
          id: 1,
          name: "水浒传",
          price: 107,
          count: 0,
          total: 0
        },
        {
          id: 2,
          name: "西游记",
          price: 192,
          count: 0,
          total: 0
        },
        {
          id: 3,
          name: "三国演义",
          price: 219,
          count: 0,
          total: 0
        },
        {
          id: 4,
          name: "红楼梦",
          price: 178,
          count: 0,
          total: 0
        },
      ],
      sum: 0
    };
  },
  methods: {
    btn(id) {
      this.arr[id-1].count++;
      this.arr[id-1].total = this.arr[id-1].count * this.arr[id-1].price
      this.arr.forEach(item => this.sum += item.total)
    }
  },
};
</script>